Chain saw



FIG. 1 is a left side elevational view of a chain saw, showing my new design;

FIG. 2 is a top right front perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a top right rear perspective view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a rear elevational view thereof; and,

FIG. 7 is a right side elevational view thereof.

The bottom surface of the chain saw forms no part of the claimed design. 

The ornamental design for a chain saw, as shown and described. 